Columnar Joints and Landscapes
Tsumekizaki is located on the coast of Suzaki Peninsula in the southern Izu Peninsula. The landscape of Tsumekizaki is characterized by vertical columns and beautiful hexagonal patterns on shore platforms produced by wave erosion. Columnar joints were created in andesite aged 6 million years. The columns, mainly six-sided, are 45 to 70 cm wide. Five-sided and seven-sided columns are also found. Double hexagons are seen on some cross sections of the columns (Photo 8). Difference between the cooling rates of the outside and inside formed this structure. The outside part rapidly cooled and the inside more slowly cooled. The outside texture is vitric and more fine-grained than the inside texture.
Photo 6: Columnar jointing at Tsumekizaki
Photo 7: Hexagonal patterns
Photo 8: Cross sections of columns
The scale is 20 cm long.
Location: Shimoda City, Shizuoka Prefecture (On
the Google map)
Izukyu Shimoda Station. Take a bus for Tsumekizaki and get off the terminal stop (22 minutes from the station). There is an observatory for columnar joints near a lighthouse. Walk down to the beach from the observatory to access the outcrop of columnar joints.
A good trail along the coast is available to look the coast landforms and strata from Tsumekizaki to Suzaki (2.8 km). At Suzaki, you can take a bus for Shimoda Station.
[Names written in Japanese]
Izukyu Shimoda-eki (station): 伊豆急下田駅
Izu-hantou (peninsula): 伊豆半島